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Small asphalt roller packs a big punch

The CASE line of small double-drum asphalt rollers is ideal for parking lots, bike paths, tennis courts, and other small-to medium-size projects. CASE engineers designed each of four sizes (DV23, DV26, DV36, and DV45) to deliver the same level of productivity as its larger models, while helping to boost efficiency on jobs where space is tight, so maneuverability is paramount.

The CASE DV Series of small double-drum rollers from CNH America LLC, uses hydraulics for virtually every aspect of its operation. A pair of hydraulic motors drives each drum for maximum traction and another pair drives an eccentric weight in each drum for controller compaction. Articulated steering is provided via hydraulic cylinder.

Although compact, the small rollers incorporate design features normally found only on heavier machines — dual-vibration amplitudes, dual frequencies, and dual centrifugal forces. In addition, the smaller models are designed with hydrostatic drive and dual-drum drive systems. The rollers can handle anything from course base compaction to hot-mix asphalt. Operating weight for the rollers ranges from 4,960 lb (2,250 kg) to 10,296 lb (4,670 kg).

At first glance, an asphalt roller may seem to compact and flatten surfaces simply by its sheer weight. But spinning an eccentric weight inside the drum creates radial reaction forces that give the drum more compaction force than from gravity alone. The action is similar to compacting earth with your feet. If you stand still or walk, the earth is compacted simply by your weight. But if you jump up and down, the additional force when your feet hit the ground will compress the soil more than by simply standing on it.

A drive system first

At the time they were introduced in March 2013, the DV Series rollers were the first rollers in the small, double-drum size class to incorporate a drive-by-wire system instead of a cable-to-stroke system. The vehicle’s hydrostatic drive uses an electrically operated travel lever to engage a Bosch Rexroth variable-displacement piston pump for smooth and precise starting and stopping in forward or reverse. The electronic control system replaces a direct cable traditionally found on small rollers and lets the operator achieve a better finish by virtually eliminating lurching that can cause divots. The electronic travel lever also eliminates the need for cable maintenance of a mechanical cable.

The travel lever can be adjusted for slower or faster response times to match an operator’s preference. Working in tandem with the Bosch Rexroth controller, the system also ensures smooth travel throughout the machine’s full range of motion.

A unique hydrostatic drive system adds to the travel smoothness of the DV Series rollers. Unlike many small rollers propelled by only one drum drive motor, independent pumps on the DV Series rollers drive both the front and rear drums to deliver 100% traction efficiency, which eliminates slippage on the compacted surface. A traction control feature also lets users regulate hydraulic oil flow to the drums to gain maximum traction when negotiating steep grades. Maximum travel speed for the rollers is 6.2 mph (10 km/hr)

Unique vibration system

The small DV Series rollers are also unlike most rollers in their size class because they provide dual amplitudes and dual frequencies. The result is consistent frequency and impact force — both of which allow users to adapt to conditions and achieve the desired level of compaction, as well as a quality asphalt mat finish.

A vibratory selection switch lets users initiate vibration to the front drum or both drums. When the switch is in the vibration-off position, hydraulic oil continuously flows throughout the closed-loop system. Activating the vibration switch routes a controlled amount of oil to one or both drums based on the operator’s choosing. The larger DV36 and DV45 models allow for even more precise vibration amplitude control with higher or lower settings.

The DV rollers also offer manual or automatic vibration control. Manual mode gives experienced operators total control over starting and stopping vibration. Automatic mode only initiates vibration when the roller reaches the optimum speed for vibration and stops vibration when it falls below the optimum speed. The automatic setting minimizes the potential for divots and imperfections caused by vibration when the roller is stopped or traveling too slowly to achieve optimal compaction.

Of course, the drum vibration should not be transmitted to the operator, so a vibration-damping operator platform minimizes vibration to reduce operator fatigue.

The rollers’ Tier-4 Interim Yanmar engine delivers enough power to the hydraulics to generate the same high centrifugal forces and frequencies as other manufacturers’ machines, but at lower speeds to save on fuel. Low and high frequencies are 58 or 66 Hz for DV23 and DV26 models and 45 or 57 Hz for the DV36 and DV45 rollers. Centrifugal force delivered by the rollers is 9,217 lb for the DV23 and DV26 models; 11,240 lb for the DV36 roller; and 11,690 lb for the DV 45 roller.

Designed for tight spaces

The small DV Series rollers are suitable for virtually any situation where maneuverability and finesse is a must. The rollers feature a tapered offset drum and high curb clearance, allowing operators to compact right up to high curbs or other tight areas without having to worry about making marks or cutting the pavement.

Each roller also provides a tight turning radius for its size — as small as 93 in. (2,350 mm). The tight turning radius improves compaction times, and offset tapered drums reduce asphalt tearing while compacting around curves.

Steering is provided by an articulated joint that is controlled by a hydraulic cylinder. A maintenance-free Teflon bearing on articulated joint eliminates the need for greasing.

Covering all the bases

The CASE DV Series double-drum rollers were designed knowing that productivity is key to asphalt contractors, whether they’re working on a small to medium-size job — or one that requires a machine that can make quick work of tight spots encountered on almost any job at almost any time.